Platinum-resistant cancer treatment

ABSTRACT

A compound of formula I or a pharmaceutically acceptable salt or ester thereof is provided for the treatment of cancer wherein (i) the cancer is one that has the characteristic of being a type prone to being or becoming refractory or resistant to platinum drug based therapy and (ii) the treatment is with a dose of between 1 mg/m2 and 30 mg/m2 of compound per patient body surface area per administration. Method of treatment and novel dosage forms are also provided. Particularly treated are ovarian cancers, particularly those expressing a-folate receptors, including epithelial ovarian, fallopian tube or peritoneal cancer.

The present invention relates to novel treatment for cancer, moreparticularly for cancers that often show resistance to, or are otherwiserefractory to, platinum based therapy. Particular cancers that are to betreated include ovarian, endometrial, mesothelial and non-small celllung (NSCL), and cancers derived from these. More particularly preferredtreatment is provided for ovarian derived cancers such as epithelialovarian, fallopian tube and peritoneal.

Most particularly the present invention provides novel treatment forsuch cancers that carry α-folate receptors (FR-α), and especially thoseshowing higher than background non-cancerous tissue levels of α-folatereceptors, and particularly those having those FR-α on the surface oftheir cellular membranes. Cancers suitable for the present treatmentalso include FR-α expressing breast and lung cancers, particularlytriple negative breast cancer.

The α-folate receptor is overexpressed in many carcinomas, particularlythose of ovarian origin where it is overexpressed highly andhomogeneously in 90% of cases; see Cancer Res. 51, 5329-5338, 1991(Campbell et al., 1991). Furthermore, high α-FR expression has beenlinked to aggressive, platinum resistant disease and poor prognosis—seeInt. J. Cancer 74, 193-198, 1997 and Int. J. Cancer 79, 121-126, 1998(both Toffoli et al.). The β-isoform is widely expressed in tumours ofepithelial and non-epithelial origin with expression levels beinggenerally low/moderate and high, respectively, reviewed in Critical Rev.Therap. in Drug Carrier Systems 15, 587-627, 1998 (Reddy and Low).

The present invention particularly advantageously provides a treatmentfor patients with High-Grade Serous Ovarian Carcinoma (HGSOC), such asin the salvage setting where there is high unmet medical need forproducts that are able to extend life.

Ovarian cancer is a term for a group of tumours that arise from diversetypes of tissue contained in the ovary. The most common type of ovariancancer arises from epithelial cells on the surface of the ovary, and canoften spread to any surface within the abdominal cavity including thefallopian tubes and peritoneal cavity. Fallopian tube cancer and primaryperitoneal cancer are histologically equivalent diseases to epithelialovarian cancer. Ovarian cancer is classified from Stage I to Stage IV.Advanced ovarian cancer falls within Stages III and IV; Stage IIIdenotes disease that is locally advanced and has spread outside thepelvis into the abdominal cavity and Stage IV denotes that distantmetastasis to other body organs such as the liver and lungs hasoccurred.

Epithelial ovarian cancers (EOCs) are the most common cause of deathfrom gynaecological malignancy in the developed world. EOCs comprise aheterogeneous group of neoplasms including serous (68%), clear cell(13%), endometrioid (9%) and mucinous (3%) pathological subtypes. Serousovarian carcinomas are further divided into low-grade (type I) andhigh-grade (type II) serous ovarian carcinomas (LGSOC and HGSOC,respectively). Most deaths are attributable to HGSOC which isapproximately 20 times more common than LGSOC.

Ovarian cancer may be categorised according to the response to initialplatinum chemotherapy as follows:

-   -   platinum-sensitive-disease responds to platinum-based therapy        but may relapse after 6 months or more, which can be subdivided        into        -   fully platinum-sensitive-disease responds to platinum-based            therapy but relapses after 12 months or more and        -   partially platinum-sensitive-disease responds to            platinum-based therapy but relapses between 6 and 12 months;            and    -   platinum-resistant-disease which relapses within 6 months of        completion of platinum-based chemotherapy and    -   platinum-refractory-disease does not respond to initial        platinum-based chemotherapy.

Although a significant percentage of people have disease that respondsto initial chemotherapy, between 55% and 75% of these relapse within 2years of completing treatment. In addition to these scenarios, somepatients are intolerant to treatment with platinum based drugs and thuswill also need alternate options to platinum that the regimens of thepresent invention now provide.

The initial therapeutic approach for HGSOCs is usually surgical tumordebulking followed by chemotherapy. Optimal debulking, with nomacroscopic residual disease, is the most important prognosticindicator. However, as HGSOC is asymptomatic in the early stages mostpatients present with advanced stage disease.

Most HGSOCs (80%) respond well to platinum/taxane therapy initially,with drug resistance emerging during subsequent treatment cycles.However, a minority of HGSOC cases (20%) are refractory toplatinum-based chemotherapy from the time of presentation, but the basisfor this drug resistance is not known. Disease Stages III and IV, apreferred target population for the present treatment, have a high rateof recurrence.

Patients with optimally debulked (≤1 cm) Stage III ovarian cancer aretypically offered intraperitoneal (IP) chemotherapy after front-linesurgery. At this time, there is no standardized regimen for IP therapy;however, dosing regimens with drugs such as paclitaxel and cisplatin, ora carboplatin regimen may be used. If the patient cannot tolerate IPdelivery then intravenous drug may be given such as paclitaxel andcarboplatin or docetaxel plus carboplatin.

Treatment of Stage III and IV disease is usually with chemotherapy; thetreatment choice depends on the time elapsed since previous completeresponse to platinum-containing chemotherapy. Although liposomaldoxorubicin is a good first choice, there are many agents with similarefficacy and the final choice depends on individual circumstance andpatient and physician preference. Some of the drugs available includeGemcitabine, Topetecan, Paclitaxel, Docetaxel, Etoposide andNanoparticle albumin-bound paclitaxel. Consideration may also be givento bevacizumab as a single agent or in combination with paclitaxel,pegylated liposomal doxorubicin, or topotecan.

Other possible therapies in drug company pipelines include PARPinhibitors, such as Lynparza (olaparib) and Rubraca (rucaparib) (bothlabels limited to BRCA mutations) and Zejula (niraparib); and checkpoint inhibitors such as Tecentriq (atezoizumab) and Bavercio (avelumab)for non BRCA mutations. However many key opinion leaders have expressedthe belief that such drugs need to be used with more clearly identifiedpopulations to be capable of increasing overall response rates. Keytruda(pembrolizumab) has also been found to have some efficacy where highlevels of PD-1 are found on T-lymphocytes and tumours.

Several FR-α targeted drugs have been put into clinical trials. The FR-αtargeted monoclonal antibody Farletuzumab failed to improve progressionfree survival (PFS) in patients with platinum-sensitive epithelialovarian cancer in a 1,100 patient Phase III clinical in combination withpaclitaxel and carboplatin. Vintafolide, a conjugate of an α-folatereceptor targeting moiety with Vinblastine, has shown some success atimproving PFS in combination with docetaxel in folate receptor positivenon-small cell lung cancer (NSCLC) and has been trialled together withpegylated liposomal doxorubicin (PLD) in ovarian cancer but the Phase HItrial failed to meet the prespecified criteria for PFS to allowcontinuation of the study. Antibody-drug conjugate IMGN853 (mirvetuximabsoravtansine) has also been through Phase I trial in platinum resistantepithelial ovarian cancer with some indication of potential forincreasing PFS at a dose of 6 mg/kg every three weeks with PFS of 6.7months in 39% of patients who had three or less prior lines of therapy.

Despite the possibility that combinations of these agents may proveuseful in the platinum resistant setting, there remains a need fortreatment of platinum resistant cancers and particularly ovarian cancerssuch as HGSOC as it accounts for the most ovarian deaths and has shownlittle improvement in overall survival for decades. Whereas potentialblockbuster drugs such as immune checkpoint inhibitors have yieldedimpressive clinical responses in melanoma and non-small cell lungcancer, possibly due to exceptionally high mutational loads, by contrastHGSOC has intermediate mutational load with lower numbers of neoantigensexpected. (Bowtell et al. Nat Rev Cancer 2016 June). Current singleagent HGSOC therapies have overall response rates (ORR) of 15-20% andprogression free survival (PFS) of only 3 to 4 months.

A further drug class includes the thymidylate synthase (TS) inhibitorsCB3717, ZD1694 (raltitrexed), LY231514 Alimta (pemetrexed) and ZD9331(plevitrexed). All of these TS inhibitors have demonstrable clinicalactivity in a range of solid tumours (see Cancer Treatment Reports,1986, 70, 1335 and Beale et al., “Tomudex: Clinical Development” inAntifolate Drugs in Cancer Therapy (ed. Jackman), Humana Press, Totowa,N.J., USA, pp. 177-181, 1999). Side-effects of raltitrexed and ZD9331are predominantly related to inhibition of TS in gut and bone-marrow.

Raltitrexed and pemetrexed are examples of “classical” TS inhibitorsdefined by the following properties: the reduced foliate carrier (RFC)is the main transporter into cells; they are excellent substrates forfolylpolyglutamate synthase (FPGS) and thus extensively polyglutamatedin tissues/tumours to polyglutamates which are effective cytotoxic drugspecies; and they have fairly short half-life in plasma. Because theseclassical inhibitors are cleared slowly from tissues because ofpolyglutamation, they are often cytotoxic and are used in an infrequentshort-infusion, eg. about 15 min, dosing regimen at high dosages.

Plevitrexed is a “non-classical” TS inhibitor in that it is notpolyglutamated and is has the following properties: the RFC is the maintransporter into cells; it is not a substrate for FPGS; TS Ki˜0.4 nM,i.e. similar to polyglutamates of raltitexed and pemetrexed; it isreadily effluxed from cells and thus not retained well intissues/tumours; and has a long plasma half life.

Whilst pemetrexed has been approved for use in non-small cell lungcancer and pleural mesothelioma, it has also been proposed as atreatment for platinum-resistant ovarian cancer. For example in thisindication 500 mg/m² pemetrexed was given on day 1 and gemcitabine onday 8 of a 21 day cycle (Clin Transl. Oncol (2009) 11:35-40 and at 900mg/m² once every 21 days (J. Clin Oncol 27: 2686-2691). Furtherdiscussion of these trials and others is provided in Expert Opin.Investig. Drugs (2012) 21(4) and Expert Opin. Investig. Drugs (2013)22((9) the latter of which notes a recommended single agent pemetrexeddose of 600 mg/m². This paper also notes that at that date no antifolatedrug, which TS inhibitors are, had been approved for the treatment ofovarian cancer.

A further subset of this group of TS inhibitor compounds are FR-αtargeted cyclopenta[g]quinazolines, described in patent applicationsWO-A-94/11354, WO-A-95/30673 and WO-A-03/020748. U.S. Pat. Nos.5,789,417, 5,747,499, 7,250,511, 7,297,701, 7,528,141, 7,705,006,7,863,284, 8,063,056, 8,486,955 and 8,552,016 are incorporated herein byreference for purposes of US patent rights. These documents teach thatthese compounds be administered at a dose within a range of 50-25000,particularly 50-5000, mg per square metre body area patient (mg/m²),i.e. approximately 1500 mg/m², particularly 1-100 mg/kg. Higher dosagesare taught could be employed and where subcutaneous infusion is usedthat the dose range may be increased to 1-1000 mg/kg, preferably 10-250mg/kg, particularly 30-150 mg/kg.

These inhibitors may also be used against other cells expressing FR-β,in contrast to FR-α, particularly those involved in rheumatoid arthritisand acute myeloid leukemia. For this purpose U.S. Pat. No. 8,466,111teaches a dose within the range 50-25000 mg/m², but also lists 5-25000mg/m² but states that for subcutaneous administration the dose isincreased to 1-1000 mg/kg or 0.1-10 mg/kg. There is discussion oftopical administration at 0.1 to 10 mg/kg and oral tablets containing 1,10, 50 and 100 mg of compound are disclosed as is an injection solutionof 1, 10 and 50 mg/ml.

The higher dosages used are consistent with raltitrexed and pemetrexedand this subset of TS inhibitor compounds share similar properties suchas: FR is the main transporter; uptake via FR is slower and more easilysaturable than is RFC-mediated uptake of other antifolates; they are nota substrate for FPGS; and TS Ki˜1.4 nM, which is similar topolyglutamates of raltitexed and pemetrexed. But because the compoundsare readily effluxed from cells not retained in tissues/tumours, it wastaught that high dosages should be tolerable.

Typically, TS requires inhibition for at least 24 hours to induceantiproliferative effects, and adequate intracellular exposure to drugof at least 2 to 3 days repeated frequently e.g. weekly for TSinhibitors to be effective. This is achieved by polyglutamation ofraltitrexed and pemetrexed which overcomes the short plasma half-lifeand short extracellular exposure. Long intracellular exposure withplevitrexed, for example, is achieved by the unusually long plasma finalhalf-life providing prolonged extracellular exposure.

Surprisingly on administration of the lead compound of this newer classFR-α targeted TS inhibitors to man half life levels were found to beunusually long. This compound, ONX-0801 (hereafter BTG945) has a highaffinity for the alpha-folate receptor (FR-α) and enters cells via FR-αmediated transport. It has a modified glutamate ligand, L-glu-y-D-gludipeptide, and so is not a substrate for FPGS. It binds the α-FR with anaffinity that is 70% of folic acid (FA) (Theti et al., 2003); it bindsFR-β with similar affinity (van der Heijden et al., 2009) and it appearsto have negligible affinity for the ubiquitous reduced folate carrier(RFC) except at high concentrations (Gibbs et al., 2005). This, it hasbeen found, leads to a targeted concentration and time-dependentinhibition of tumour cell proliferation in vitro.

Once inside the cell, BTG945 binds irreversibly to the active site ofthymidylate synthase, which is then prevented from performing its normalrole in generating thymidine monophosphate (dTMP), a key step in DNAsynthesis and repair similarly exploited by the approved TS-inhibitors.

A first in human Phase I clinical trial of BTG945, identified therein asONX801, was initiated 30 Sep. 2009 with trial registration numberISRCCTN79302332 with the aim of finding a tolerable dose for 3 hourinfusion on days 1, 8 and 15 of a 21 day cycle which would inhibittumour cell growth. However, this trial was abandoned 30 Mar. 2011 dueto toxicity at the predicted therapeutically effective dose of 45 mg/m²with incidence of Brochiolitis Obliterans with Organising Pneumonia(BOOP), irreversible and believed to increase with culmulative dose.This lead to the conclusion that the drug could not be used at thepreconceived dose and regimen as this toxic dose was less than thattaught as preferred minimal dose for treatment.

Given the high unmet need for the target treatment cohort, the presentinventor has reassessed the dosage regimen that might be applied to thedrug BTG945 to render it clinically useful. Analysis of unpublishedhuman plasma drug levels suggested that much lower doses of drug wouldbe necessary to avoid toxicity. The inventor and applicant initiated anew Phase I trial, EudraCT3941, at these presumed safe but predictednon-therapeutic doses wherein it has now been found that unexpectedefficacy against platinum resistant tumours, particularly FR-αexpressing tumours, in human patients is provided at far lower levels ofdrug than had previously been thought necessary and without occurrenceof the treatment limiting BOOP. This efficacy has been exhibited aspartial responses, using RECIST criteria, and stable disease, providingperiods of progression free survival, particularly providing partialresponses and/or objective response rates (ORR) in high percentages ofovarian cancer patients showing α-folate receptor expression,particularly when such expression exibits receptor on tumour membranes.

So, whilst BTG945 has comparable Ki to raltitrexed and pemetrexedagainst isolated target thymidine synthase (1.2 nM as compared to 1.4nM), the doses required to have efficacy in man are considerably lessthan those previously envisioned yet in the FR-α expressing preferredtarget group the compound appears to have efficacy far superior to thatseen with other members of the TS inhibitor class.

Particularly surprising and advantageous is the finding that the sideeffect profile of BTG945 is unusually favourable. Dose limiting effectsother than BOOP were not seen and BOOP itself has proven manageableand/or may be eliminated by optimised regimens using for example 2 or 3weekly dosing. Side effects such as neutropenia, diarrhoea and hairloss, normally associated with thymidine synthase inhibitors, were notobserved, nor were side effects associated with α-folate receptorantibody conjugates, such as diarrhoea, blurred vision and nausea.Furthermore conventional toxicities associated with cytotoxicchemotherapy, such as myelotoxicity, nephrotoxicity and neurotoxicity,were not observed.

Some trial patients' cancers were shown to respond at as low as 1 mg/m²in the treatment regimen outlined below. Side effects determined to datesuggest that this regimen may be employed as monotherapy or incombination with any of the currently employed therapies describedherein as toxicities are not overlapping. Such findings in the clinicalsetting now provide treatment of platinum resistant cancer that can beused as monotherapy or in combination with other available treatmentswith promise of extending PFS in a patient group with remaining highunmet need. Combination of the present treatment with first linetreatments such as paclitaxel or carboplatin particularly are madeavailable.

In a first aspect the present invention provides a compound of formula I

or a pharmaceutically acceptable salt or ester thereof for the treatmentof cancer wherein(i) the cancer is one that has the characteristic of being a type proneto being or becoming refractory or resistant to platinum drug basedtherapy and(ii) the treatment is with a dose of between 1 mg/m² and 30 mg/m² ofcompound per patient body surface area per administration.

The treatment is preferably with a dosage regimen that results in plasmaconcentration of drug 0.5 μM or greater for at least 72 hours. Morepreferably the dosage regimen results in a plasma concentration of drugimmediately after dosing that is from 1 μM to 5 μM for no more than 72hours, preferably for no more than 60 hours. Most preferably the dosageregimen maintains the plasma concentration of drug from 0.1 μM to 2 μMfor at least 50% of the treatment cycle period.

The treatment is preferably with a dosage regimen selected from

-   -   a dose of 1 to 10 mg/m² administered in a 28 day cycle at 7 day        intervals on day 1, 8, 15 and 22.    -   a dose of 6 to 14 mg/m² administered in a 28 day cycle at 14 day        intervals on day 1 and 15    -   a dose of 10 to 30 mg/m² administered in a 21 day cycle on day        1.

The cancer is preferably one that is platinum refractory or resistant.Preferably the cancer is selected from ovarian, endometrial,mesothelial, non-small cell lung or a cancer derived from one of those.

More preferably the cancer is selected from those expressing α-folatereceptors (FR-α) and especially those showing higher than backgroundnon-cancerous tissue levels of α-folate receptors. Most preferably theFR-α is expressed on the surface membranes of the cancer cells. Mostpreferably the cancer is an ovarian cancer such as epithelial ovarian,fallopian tube or peritoneal cancer, but may also be breast or lungcancer, for example triple negative breast or non-small cell lung.Specifically preferred cancer to be treated is serous ovarian cancersuch as High-Grade Serous Ovarian Cancer (HGSOC) such as found in thesalvage setting.

For the avoidance of doubt, platinum drug based therapy includes, but isnot limited to, that with drugs Cis-platin or Carboplatin.

Whilst treatment with doses from 1 mg/m² to 30 mg/m² is included in thescope of the invention, preferred doses are from 3 mg/m² to 30 mg/m² ofcompound per patient body surface area per administration, morepreferably doses of 5 mg/m² to 20 mg/m² of compound per patient bodysurface area per administration, still more preferably a dose of 8 mg/m²to 15 mg/m², most preferably 10 mg/m² to 15 mg/m² and particularly about12 mg/m², eg. 11.5 mg/m² to 12.5 mg/m² of compound per patient bodysurface area per administration.

The dose is preferably administered intraperitoneally (IP) orintravenously (IV). IP administration will allow dosing with less riskof systemic side effects, particularly those that would affect the lungssuch as BOOP. Typically the dose is administered intravenously.

In one preferred embodiment of the invention the compound isadministered intraperitoneally (IP) as an injection, particularly asingle injection, in a suitably sized volume, for example from 1 ml to10 ml, more preferably 2 ml to 6 ml containing an appropriate amount ofcompound to meet the mg/m² dosage requirement. Typical such doses willbe 2, 3, 4 or 5 ml of solution. Typically being an aqueous solutionwhich may be in saline or in water for injection. The compound here isthe ‘Drug Substance’ and the ‘Drug Product’ is a vial with theappropriate volume for a single IP administration. In a furtherpreferred embodiment, multiple IP injections are given each as from 1 mlto 10 ml, but more preferably 2 ml to 6 ml solution containing theappropriate mg of Drug Substance. Typical such doses will be 2, 3, 4 or5 ml of solution. Each ‘Drug Product’ provides for single or multiple IPinjections and the Drug Product is a vial containing the Drug Substance,for example being a glass vial, eg a clear glass vial, with a stopperand suitable fixing to maintain the stopper in place such as analuminium crimp seal.

In a further preferred embodiment, the compound is convenientlyadministered by injecting the content of a vial provided bypharmaceutical company supplier into a sterile saline bag as part of asaline drip. Typically the ‘Drug Product’ is a sterile aqueous solutionof the Drug Substance BTG945 as trisodium salt, preferably being thedihydrate in solid form. The Drug Product is contained for example in aType 1 clear glass vial, with a stopper and aluminium crimp seal. Thelabelled strength of each vial includes for example a 2-mL solutioncontaining the appropriate mg of the Drug Substance. Conveniently, theonly excipient in the BTG945 trisodium salt Drug Product can be sterilewater for injection. Other components conventional in pharmaceuticalcompositions may of course be provided.

Drug Product vials are typically stored at low temperature and they arethawed prior to use, then the desired aliquot is withdrawn from 1 ormultiple stoppered vials using a sterile syringe. This aliquot is thendirectly added to an infusion bag for further dilution in 250 mL of 0.9%sterile saline (USP) for injection, whether IP or IV. Once diluted intoinfusion bags, the prepared solution should preferably be administeredto patients at ambient temperature within 24 hours. Prior toadministration, the vials and bags should be protected from light.

In one preferred embodiment for IP infusion the aliquot is directlyadded to an infusion bag for further dilution in 10 ml, 15 ml, 25 ml or50 ml of 0.9% sterile saline (USP) for IP injection or infusion. Oncediluted these bags are treated as previously described.

More particularly the invention treats with the said calculated dose byinfusions, particularly intravenous infusions (IV) or as single ormultiple injections, as set out above spaced between 10 and 28 daysapart, more preferably between 10 and 21 days apart and most preferablyat dosing interval of about 14 days or 21 days. Still more preferably,when administered IV, the invention treats with a cumulative maximum of150 mg/m² of compound per patient body surface area over the course ofall infusions. More preferably this limit also applies to IP dosaging.More preferably the maximum cumulative dose is 144 mg/m².

Treatment in accordance with the present invention provides the compoundpreferably in infusions 14 or 21 days apart in 21 or 28 day cycles, mostpreferably 28 day cycles of two infusions each cycle, one on day 1 andone on day 15. These cycles are preferably repeated until the maximumcumulative dose is reached. Infusions are preferably carried out over0.5 to 3 hours. As the treatment may be effective using as little as 1mg/m² it will be realised that infusion rates of 1 hour will besufficient. Thus infusions may be carried out over 0.5 to 1 hour, over 1hour, but fewer than 3 hours.

More preferred dosages for each administration, eg infusion, are 1 mg/m²to 20 mg/m², preferably 3 mg/m² to 20 mg/m², more preferably 6 mg/m² to18 mg/m², still more preferably from 8 mg/m² to 16 mg/m², eg from 10mg/m² to 15 mg/m² and from 10 mg/m² to 12 mg/m². The most preferred doseis about 12 mg/m². At a 12 mg/m² dose given in 28 day cycle once every14 days it can be seen that the maximum cumulative recommended dose willbe reached in just under 6 months. A further preferred dose is a 12mg/m² dose given once every 21 days in 21 day cycles. Further dosing mayconsidered if the attending clinician is monitoring for the irreversibleBOOP or similar side effect. When patients show signs of BOOP, forexample if there is evidence of accumulation of inflammatory cellularexudate (AICE) on CT scan, the dose of drug compound should be reduced.It may also be prudent to stop drug administration for a short period,eg. 2 or 4 weeks, and then recommence with a lower preferred dose. ACIEhas been observed on radiological scans, and it has been found that thecondition stopped development or was reduced by halting dosing at 12mg/m² for 2 weeks and then recommencing at 6 mg/m² until the maximumcumulative dose of 144 mg/m² is achieved.

In a particularly preferred embodiment, the preferred dosageadministered achieves a blood concentration of about 0.5 μM or greaterof the compound for at least 72 hrs, preferably less than 2.0 μM andmore preferably about 0.7 μM or greater is achieved for at least 36 hrsor even more preferably about 0.9 μM or greater is achieved for at least24 hrs, more preferably also being less than about 1.5 μM. This level isparticularly preferred for IV administration. It is preferred that bloodplasma levels of drug do not remain over 1 μM for more than 72 hours.Most preferably the dosage regimen maintains the plasma concentration ofdrug from 0.1 to 2 μM for at least 50% of the treatment cycle period.More preferably 0.1 to 1 μM for 50% of said period.

One particularly preferred cohort of suitable cancers for the treatmentof the invention are those of female patients with newly diagnosed,histologically confirmed, high risk advanced (FIGO stage III-IV) BRCAmutated high grade serous or high grade endometrioid ovarian cancer,primary peritoneal cancer and/or fallopian-tube cancer.

Stage III patients preferably have had one attempt at optimal debulkingsurgery (upfront or interval debulking). Stage IV patients preferablyhave had either a biopsy and/or upfront or interval debulking surgery.

Particularly preferred are cancers of patients who have completed firstline platinum (e.g. carboplatin or cisplatin) therapy (intravenous orintraperitoneal).

Most effectively treated by the present treatment are cancers thatexpress α-folate receptors, particularly those expressing α-folatereceptors on the membranes and/or in cytoplasm of at least 25% of cellsof the cancer. More effectively treated are cancers that expressα-folate receptors on or in at least 50% of the cells of the cancer andmost effectively those expressing α-folate receptors on or in at least75% of the cells of the cancer. Such levels may be determined byhistological investigation of biopsy tissue using α-folate specificantibodies linked to visualisation agents as known in the art. Formaximal efficacy the cancers are those that express FR-α on the cellmembranes.

An example of a method for assessing α-folate receptor expression onmembranes and in cyctoplasm is described in Kurosaki et al (2016) Int.J. Cancer: 138, 1994-2002 VC 2015 UICC where the tumour FR-α expressionon FFPE (formalin-fixed paraffin-embedded) specimens was investigatedusing a specific antibody NCL-L-FRalpha (clone BN3.2; Leica Biosystems,UK) on a total of 164 EOCs, including borderline malignancies.Immunohistochemical staining was performed on full section slides usinga BenchMark XT automated slide stainer and an iView DAB detection kitaccording to the manufacturer's instructions (Ventana Medical Systems,Tucson, Ariz.). Sections were deparaffinized, hydrated and antigenretrieval with Cell Conditioning Solution 1 (Ventana Medical Systems),followed by the mouse monoclonal anti-FRA antibody (1:40 dilution)incubation for 30 min. Positive staining was defined as the presence ofmembranous or membranous with cytoplasmic stain in tumor cells. Slideswere scored as <1% positive tumor cells staining as negative, 1-25%positive tumor cells staining as weak (11), 25-75% staining as moderate(21) and greater than 75% staining as strong (31). The scoring of FR-αstaining was evaluated in a blinded fashion by two independentobservers. Any discrepancies were resolved by joint review over adouble-headed microscope.

An alternative method for non-invasively ascertaining the suitability ofa patient for treatment using the present invention assays for α-folatereceptors in the blood. Such assays are described for example Basal etal (2009) PLoS ONE 4(7): e6292. Doi:10.1371/journal.pone.0006292, atleast for ovarian cancers. Where α-folate receptor is found onmembranes, it can be shed into circulating physiological fluids such asblood serum. In the case of ovarian cancer that team have found thatpatients with ovarian cancer have elevated levels of circulatingα-folate receptor (FRα). This was found to be the case even where thecancer was in its early stages.

Kurosaki et al (2016) Int. J. Cancer: 138, 1994-2002 further confirm theapplicability of serum α-folate receptor levels for diagnosing ovariancancers of epithelial origin and correlated high serum FR-α with shorterPFS.

In addition to the ovarian tissue derived cancers specified above, FR-αoverexpressing cancers that are suitable for treatment by the method andregimens of the invention also include cancers of the uterus,mesothelium, kidney, stomach, lung, colon, choroid plexus and brain. Thehighest levels of overexpression have been detected in non-mucinousovarian cancer (Toffoli et al., 1998) where >90% of patients' tumoursexhibit overexpression of the FR-α, but high levels have also beendemonstrated in papillary serous endometrial cancer (Allard et al.,2007) renal cell cancer, and NSCLC (Parker et al., 2005). In addition,breast, primary CNS, colon and gastric cancers show varying degrees ofexpression (Low and Kularatne, 2009).

TABLE 1 Alpha-Folate Receptor Expression in Selected Tumours (Weitman1994; Garin-Chesa 1993; Bueno 2001) Tumour Type % tumours overexpressingFR-α Ovary 92% Uterus 91% Mesothelium 70% Kidney 50% Stomach 38% Lung33% Colon 22% Choroid plexus 80% (ependymal) Brain 80% (metastases)

The compound for use in the present invention has IUPAC nomenclatureN-{N-{4-[N-((6S)-2-Hydroxymethyl-4-oxo-3,4,7,8-tetrahydro-6H-cyclo-penta[g]quinazolin-6-yl)-N-(prop-2-ynyl)amino]benzoyl}-L-γ-glutamyl}-D-glutamicacid or is a salt thereof and is herein referred to as BTG945, of whichthe trisodium salt thereof has the general formula II

Alternate nomenclature is D-glutamic acid,N-[4-[2-propyn-1-yl-[(6S)-4,6,7,8-tetrahydro-2-(hydroxymethyl)-4-oxo-3H-cyclopenta[g]quinazolin-6-yl]amino]benzoyl]-L-gamma-glutamyl-,sodium salt.

The (6RS) racemate is also known to be an active form containing theactive (6S) as described. It will be realised that doses may need to beat the higher end of the described ranges if they use the racemate as itcontains only 50% of the (6S) form.

Where the compound is provided as an ester, this may be of a simplealcohol conjugated with one or more of the carboxylate moieties, whichotherwise would be sites of sodium linkage in the formula above. Theresulting alkyl esters may be any of those equivalent to the parentcompound for regulatory purposes. A suitable pharmaceutically-acceptableester form of the cyclopenta[g]quinazoline for the treatment of theinvention is, for example, an ester with an aliphatic alcohol of up to 6carbon atoms, for example a methyl, ethyl or tert-butyl ester. As threecarboxy groups are present a salt or ester may be mono-acid-di-salt or-ester, di-acid-mono-salt or -ester or even tri-salt or -ester may beused.

A suitable pharmaceutically-acceptable salt form of the compound for thetreatment of the invention is, for example, an acid addition salt withan inorganic or organic acid, for example hydrochloric, hydrobromic,trifluoroacetic or maleic acid; or an alkali metal, for example sodium,an alkaline earth metal, for example calcium, or ammonium, for exampletetra(2-hydroxyethyl)ammonium, salt. Most preferred is the trisodiumsalt.

The cyclopenta[g]quinazoline or salt described in the treatment of thepresent invention are believed in part at least to function asanti-cancer agents due to its ability to inhibit the enzyme thymidylatesynthase.

The cyclopenta[g]quinazoline or salt composition may be in a formsuitable for oral use, for example a tablet, capsule, aqueous or oilysolution, suspension or emulsion; a form suitable for topical use, forexample a cream, ointment, gel or aqueous or oily solution orsuspension; a form suitable for nasal use, for example a snuff, nasalspray or nasal drops; a form suitable for vaginal or rectal use, forexample a suppository; a form suitable for administration by inhalation,for example as a finely divided powder such as a dry powder, amicrocrystalline form or a liquid aerosol; a form suitable forsub-lingual or buccal use, for example a tablet or capsule; or a formsuitable for parenteral use (including intravenous, subcutaneous,intramuscular, intravascular or infusion use), for example a sterileaqueous or oily solution, emulsion or suspension. In general the abovecompositions may be prepared in a conventional manner using conventionalexcipients.

The preferred form of compound is for parenteral administration.Particularly preferred is compound for infusion, where the compound ispreferably formulated with saline or water for injection. Alternativelyit is provided in solid format ready to be admixed with said water orsaline. For example the dihydrate of the trisodium salt. The compositionmay contain, in addition to the cyclopenta[g]quinazoline used in theinvention, one or more other anti-cancer substances or palliativesubstances selected from, for example, other antimetabolites, DNAinteracting agents, immune-oncological agents, tumour blood vesselinhibiting agents or signal transduction inhibitors or other inhibitorsof deregulated pathways in tumours.

However, those skilled in the art will realise that more conventionally,such combinations are administered separately but coordinated in timewith treatment visits to the site of administration.

Particular regimens that are preferred to be employed with the compoundfor treatment of cancer of the first aspect of the invention are withone or more further anticancer agents selected from Cisplatin,Carboplatin, Doxorubicin, Bevacizumab Gemcitabine, Topetecan,Paclitaxel, Docetaxel, Etoposide, Nanoparticle albumin-bound paclitaxel,Lynparza (olaparib), Rubraca (rucaparib), Zejula (niraparib). Tecentriq(atezoizumab), Bavercio (avelumab)

Multiple combinations may also include bevacizumab in combination withpaclitaxel, PEGylated liposomal doxorubicin, or topotecan. Further suchexamples of combinations are exemplified in the examples below.

Particularly advantageously the first aspect of the present inventionemploys doses of these combined drugs that are lower than thosepresently prescribed. This is particularly because there has been foundnot to be cross resistance to BTG945 with that to these other drugs anddesired toxic effects on target cancer cells will often be cumulative.Thus in addition to exemplary dosage regimens provided in the examplesherein, lower doses or less frequent doses of additional drugs may beexployed.

In a second aspect the present invention provides a method for treatinga patient suffering from a cancer that has the characteristic of being atype prone to being or becoming refractory or resistant to platinum drugbased therapy and wherein the treatment is with a dose of between 1mg/m² and 30 mg/m² of compound per patient body surface area peradministration of a compound of formula I

or a pharmaceutically acceptable salt or ester thereof for the treatmentof cancer.

The cancer to be treated is as described above for the first aspect ofthe invention. The method preferably treats by administering thecompound, salt or ester intraperitoneally (IP) or intravenously (IV).

The treatment is preferably with a dosage regimen that results in plasmaconcentration of drug of 0.5 μM or greater for at least 72 hours. Morepreferably the dosage regimen results in a plasma concentration of drugimmediately after dosing that is from 1 to 5 μM for no more than 72hours, preferably for no more than 60 hours. Most preferably the dosageregimen maintains the plasma concentration of drug of 0.1 to 2 μM for atleast 50% of the treatment cycle period.

The treatment is preferably with a dosage regimen selected from

-   -   a dose of from 1 to 10 mg/m² administered in a 28 day cycle at 7        day intervals on day 1, 8, 15 and 22.    -   A dose of from 6 to 14 mg/m² administered in a 28 day cycle at        14 day intervals on day 1 and 15    -   A dose of from 10 to 30 mg/m² administered in a 21 day cycle on        day 1.

Whilst treatment with doses from 1 mg/m² to 30 mg/m² is included in thescope of the invention, preferred doses are from 3 mg/m² to 30 mg/m² ofcompound per patient body surface area per administration, morepreferably doses of 5 mg/m² to 20 mg/m² of compound per patient bodysurface area per administration, still more preferably doses of 6 mg/m²to 18 mg/m² of compound per patient body surface area peradministration, yet more preferably a dose of 8 mg/m² to 15 mg/m², mostpreferably 10 mg/m² to 15 mg/m² and particularly about 12 mg/m², eg.11.5 mg/m² to 12.5 mg/m² of compound per patient body surface area peradministration.

More preferably and particularly the method treats by infusions of thedose spaced between 10 and 28 days apart, more preferably between 10 and21 days apart and most preferably at dosing interval of about 14 days or21 days. Still more preferably, when administered IV, the inventiontreats with a cumulative maximum of 150 mg/m² of compound per patientbody surface area taking into account all of the infusions. Morepreferably this limit also applies to IP dosaging. More preferably themaximum cumulative dose is 144 mg/m².

The method in accordance with the present invention provides thecompound preferably as infusions 14 or 21 days apart in 21 or 28 daycycles, most preferably 28 days. These cycles are preferably repeateduntil the maximum cumulative dose is reached. Infusions are preferablycarried out over 0.5 to 3 hours. Infusions can be carried out over 0.5to 1 hour, over 1 hour or from to 1 to fewer than 3 hours. As thetreatment may be effective using as little as 1 mg/m² or 3 mg/m² it willbe realised that infusion rates of 1 hour will be sufficient.

More preferred dosages for each infusion are 1 mg/m² to 20 mg/m², morepreferably from 10 mg/m² to 15 mg/m². The most preferred dose is about12 mg/m². At a 12 mg/m² dose given once every 14 days in 28 day cyclesit can be seen that the maximum cumulative recommended dose will bereached in just under 6 months. This is composed of 12 infusions of 12mg/m² of compound providing cumulative total 144 mg/m². A furtherpreferred dosing schedule is a 12 mg/m² dose given once every 21 days in21 day cycles. Further dosing may considered preferably only if theattending clinician is monitoring for the irreversible BOOP or similarside effect.

The method of the second aspect of the present invention furtherprovides for treatment with the compound of the formula I in combinationwith a therapeutically effective amount of one or more furtheranticancer agents.

The one or more further anticancer agents used in this combinationtherapy are preferably selected from Cisplatin, Carboplatin,Doxorubicin, Bevacizumab Gemcitabine, Topetecan, Paclitaxel, Docetaxel,Etoposide, Nanoparticle albumin-bound paclitaxel, Lynparza (olaparib),Rubraca (rucaparib), Zejula (niraparib). Tecentriq (atezoizumab),Bavercio (avelumab) and Keytruda (pembrolizumab).

Multiple combinations may also include bevacizumab in combination withpaclitaxel, pegylated liposomal doxorubicin, or topotecan. Further suchexamples of combinations are exemplified in the examples below.

Preferred combinations are with paclitaxel or carboplatin or both.

Given the nature of the side effects seen in lung in the failed trial,the inventor also contemplates that the dosage regimen of the inventionmay also incorporate administration of a steroid to alleviateinflammation of the lung.

A third aspect of the present invention provides a method for treating apatient suffering from a cancer that has the characteristic of being atype prone to being or becoming refractory or resistant to platinum drugbased therapy and wherein the treatment is with a dose of between 1mg/m² and 30 mg/m² of compound per patient body surface area peradministration of a compound of formula I

or a pharmaceutically acceptable salt or ester thereof in combinationwith an anti-inflammatory corticosteroid. Preferred corticosteroids areselected from the group consisting of prednisone, methylprednisolone,dexamethasone and prednisolone and hydrocortisone.

In a fourth aspect the present invention provides novel dosage forms ofthe compound of formula I

comprising a single dosage unit containing said compound or apharmaceutically acceptable salt or ester thereof characterised in thatthe amount of said compound in the dosage unit is between 0.5 mg and 40mg.

More preferably the dosage unit of the invention contains between 1 mgand 30 mg of the compound of formula I or salt or ester thereof. Stillmore preferably the dosage unit contains between 5 mg and 26 mg of thecompound of formula I. Most preferably the dosage unit contains between10 mg and 24 mg of the compound or salt or ester of formula I.

The preferred dosage form will be a container of the compound of formulaI or its salt or ester, more preferably the sodium salt, as a sterilesolid or aqueous solution in a medium such as water for injection orsaline. The sterile solid is preferably BTG945 or a salt or esterthereof free of other materials. Such container would be such that theliquid contained therein, or added thereto when a solid format isprovided, could be taken up into a syringe in an amount suited to thebody surface area of the patient such as to transfer the required doseof 1 mg/m² to 30 mg/m².

Preferably the dose is provided as an aqueous solution in a vial. Such adosage form or formulation will preferably be a vial containing from 1ml to 30 mls of aqueous solution of the compound for treatment, morepreferably from 1 ml to 20 ml, still more preferably from 1 ml to 10 mland most preferably between 2 ml and 6 ml. Alternatively the dose isprovided as solid form of the compound for treatment without liquid.Thus a preferred vial of the invention will contain from 0.5 mg to 40 mgof compound in 1 ml to 30 ml of aqueous solution, still more preferably5 mg to 26 mg in 1 ml to 20 ml of aqueous solution and most preferably10 mg to 24 mg in 1 ml to 10 ml of aqueous solution, eg about 6 mg or 12mg in 2 ml to 6 ml of aqueous solution.

It will be realised by those skilled in the art that pharmaceuticals areexpensive commodities and that it is desirable not to waste compound notrequired for a given treatment. As BTG945 is potentially toxic above thenow taught doses it would be inappropriate for more than required to beprovided in the clinical setting. Thus as a preferred dose per patientsurface area is 6 mg/m² or 12 mg/m² and patients typically have surfacearea between 1 m² and 2.5 m² in developed countries, with patients withunusually high BMI often capped at 2 m², it can be seen that a novelpreferred useable vial content, whether in dried solid or solution form,would be between 6 mg to 24 mg drug compound more preferred between 10mg and 24 mg drug compound. Thus vials of drug content 6 mg, 8 mg, 10mg, 12 mg, 14 mg, 16 mg, 18 mg, 20 mg and 24 mg are disclosed as novelembodiments of the invention. Particularly those where drug is in theform of dried BTG945 salt and/or its dehydrate, or its simple solutionin water or saline for injection.

The compound for the treatment of the invention may be synthesised asdescribed in the aforementioned patent applications or as set out inmore recent patent U.S. Pat. No. 8,809,526 (Onyx) and patent applicationUS2013/0345423 (Onyx).

FIGURES

FIGS. 1 to 5 show the clinical results of trial with the treatment ofthe present invention in humans.

FIG. 1: Shows the % change in tumours using RECIST criteria in patientsin the dose escalation phase of the trial of Example 1 Weekly scheduleis indicated by asterisk and an α-folate expressing tumour indicated bya cross.

FIG. 2: Shows the % change in tumours as measured by CA125 level inescalation phase of the trial of example 1. Numbers represent dose mg/m2and letters whether weekly (w) or fortnightly (f) and an α-folateexpressing tumour indicated by a cross.

FIG. 3: Shows the % change in tumours using RECIST criteria in patientsin the expansion phase of the trial of Example 1 using 12 mg/m² doseonce every 14 days in 28 day cycles. An α-folate expressing tumour isindicated by a cross.

FIG. 4: Shows the % change in tumours as measured using CA125 level inpatients in the expansion phase of the trial of Example 1 using 12 mg/m²dose once every 14 days in 28 day cycles. An α-folate expressing tumouris indicated by a cross.

FIG. 5: Shows the mean blood concentration (μ1\4) of compoundONX-0801/BTG 945 versus time (hours) for patients under different doseregimens in the escalation phase of the trial before selection of theexpansion dose.

EXAMPLES

The present invention will now be illustrated by the followingnon-limiting examples. Further embodiments will occur to those skilledin the art in the light of these.

Preferred target cancer to be treated with the following exampleregimens will be in patients with the following:

-   -   Histologically confirmed epithelial ovarian, fallopian tube, or        peritoneal cancer.    -   Platinum resistant/refractory disease, defined as disease        progression within 180 days following the last administered dose        of platinum therapy (resistant), or lack of response or disease        progression while receiving the most recent platinum based        therapy (refractory), respectively.    -   Received up to 3 lines of chemotherapy for platinum sensitive        disease, most recently platinum containing, and no prior therapy        for platinum resistant disease

Example 1: Treatment of Patients with 1 mg/m² to 12 mg/m² BTG 945(Trisodium Salt Form Compound of Formula II) as Monotherapy

Methods: A 3+3 dose escalation design was used and two IV schedules wereexplored. Schedule A, weekly dosing (QW) and schedule B, once every 2weeks dosing (Q2W). A cycle consisted of 4 weeks and treatment wasstopped after 6 cycles in both schedules. An expansion cohort toevaluate clinical activity in patients with FR-α overexpressing highgrade serous ovarian cancer (HGSOC) was initiated.

Results: 21 patients each were treated in schedule A and B exploringdoses ranging from 1-6 mg/m² and 2-12 mg/m², respectively. The doselimiting toxicity on schedule A was G3 cellulitis; no dose limitingtoxicity was seen on schedule B. The most common toxicities were fatigue15/42 (36%), nausea 9/42 (21%) and dysgeusia 5/42 (12%). Within scheduleA at 4 mg/m2, 2 patients developed suspected drug-related changes onpulmonary function tests (drop in Dlco>15%) at cycles 5 and 6,respectively. No cases of suspected drug-related drop in Dlco were notedin patients treated in schedule B. No grade 3-4 diarrhea, mucositis orneutropenia were seen in either cohort. The Cmax, AUC and half-life at12 mg/m² were 4952 ng/mL, 85170 h*ng/mL and 26 h, respectively.Pre-clinical PK-PD modelling aimed to achieve concentrations between0.05-1 μM and this was achieved for periods of 48 h at doses of 4 mg/m²and above.

Concentrations above 0.5 μM were achieved for 72 hours at doses above 6mg/m². Evidence of thymidylate synthase inhibition was observed usingFLT PET imaging See Cancer Res 68. 3827-3834. 2008 (Pillai et al).

Based on safety and PK, the recommended phase II dose (RP2D) of BTG945(was ONX801) was 12 mg/m² Q2W and an expansion in patients with HGSOCwas initiated. 5 patients with HGSOC had partial responses (PRs) in thedose escalation cohort. In the expansion cohort in patients with HGSOC,5/11 patients had PRs to date of this filing. Archival samples have beenanalysed from 8/11 patients in the expansion cohort. 4/4 AFR+ve did havePR and 4/4 AFR−ve patients did not have a PR following treatment withBTG945, respectively. RECIST and CA125 responses are shown in FIGS. 1 to4.

Conclusions: The RP2D of BTG945 is 12 mg/m² Q2W. At the RP2D, multiplepatients with AFR overexpressing HGSOC have had PRs and furtherrandomized biomarker prespecified phase II trials are warranted.

Example 2: Combination Therapy with BTG945 and Other Anti-CancerTherapies

12 mg/m² BTG945 is administered IV in saline for injection on day 1 andday 15 of a 28 day cycle over 1 hour up to a maximum of 6 cycles. One ormore of the following exemplary therapeutic regimes are administered incoordination with this treatment as follows:

Example 2.1 Liposomal doxorubicin 40-50 mg/m² IV over 30 min; every 21 d

Example 2.2 Gemcitabine 1000 mg/m² IV over 30 min on days 1 and 8; every21 d

Example 2.3 Topotecan 1.25-1.5 mg/m² IV over 30 min on days 1-5; every21 d

Example 2.4 Paclitaxel 80 mg/m² IV over 1 h weekly

Example 2.5 Docetaxel 75-100 mg/m² IV over 1 h q 21 days

Example 2.6 Etoposide 50 mg/m²/day PO for 21 days q 28 days

Example 2.7 Nanoparticle albumin-bound paclitaxel 100 mg/m 2 IV over 30min given weekly (days 1, 8, and 15) q 28 days

Example 2.8 Keytruda 200 mg iv q3 weeks with 945 at any line ofchemotherapy.

Example 3: Combination Therapy with BTG945 and Other Anti-CancerTherapies for Platinum Sensitive Cancers

12 mg/m² BTG945 is administered IV in saline for injection on day 1 andday 15 of a 28 day cycle over 1 hour up to a maximum of 6 cycles. One ormore of the following exemplary therapeutic regimes are administered incoordination with this treatment as follows:

Example 3.1 Paclitaxel 135 mg/m² IV over 24 h on day 1 plus cisplatin100 mg/m² IP on day 2 (may reduce dose to 75 mg/m²) plus paclitaxel 60mg/m² IP on day 8 for six or more cycles, provided that the disease isresponsive. The cisplatin dose may be reduced to 75 mg/m 2 IP on day 2;some clinicians give paclitaxel 135 mg/m² IV over 3 h followed bycisplatin 75 mg/m 2 IP, both on day 1 and on an outpatient basis

Example 3.2 Carboplatin treatment. Normal range of carboplatin AUC fortreatment of ovarian carcinoma is from 5 to 7.5; patients who havereceived extensive prior chemotherapy or radiation should start with anAUC<5

Example 4: Combination Therapy with BTG945 and Other Anti-CancerTherapies for Platinum Sensitive Cancers where Patient Cannot TolerateIP Administration

12 mg/m² BTG945 is administered IV in saline for injection on day 1 andday 15 of a 28 day cycle over 1 hour up to a maximum of 6 cycles. One ormore of the following exemplary therapeutic regimes are administered incoordination with this treatment as follows:

Example 4.1 Paclitaxel 175 mg/m 2 IV over 3 h plus carboplatin AUC 7.5IV over 1 h on day 1; every 21 d for six cycles or

Example 4.2 Docetaxel 75 mg/m 2 IV over 1 h plus carboplatin AUC 5 IVover 1 h on day 1; every 21 d for six cycles

Example 5: Combination Therapy with BTG945 and Other Anti-CancerTherapies for Platinum Sensitive Stage III and IV Platinum-SensitiveRecurrence Cancers

Platinum-sensitive recurrence: If recurrence occurs >6 mo from initialor subsequent complete clinical response to platinum-containingchemotherapy, the patient should be treated with 12 mg/m² BTG945administered IV in saline for injection on day 1 and day 15 of a 28 daycycle over 1 hour up to a maximum of 6 cycles together with one of theIV platinum-containing combination regimens below. The choice depends onfactors such as preexisting comorbidity, prior toxicities, and physicianand patient preference. Regimens are as follows:

Example 5.1 Carboplatin AUC 5 IV push plus liposomal doxorubicin 30mg/m² IV over 30 min; every 28 d for six cycles

Example 5.2 Paclitaxel 175 mg/m 2 IV over 3 h plus carboplatin AUC 5(Calvert) IV over 1 h; every 21 d for six cycles

Example 5.3 Paclitaxel 80 mg/m² IV over 1 h weekly days 1, 8, and 15plus carboplatin AUC 6 IV over 1 h on day 1; every 21 days for sixcycles

Example 5.4 Docetaxel 75 mg/m² IV over 1 h plus carboplatin AUC 5 IVover 1 h; every 21 d for six cycles

Example 5.5 Gemcitabine 1000 mg/m² IV over 30 min on days 1 and 8 pluscarboplatin AUC 4 IV over 1 h on day 1; every 21 days for six cycles

Example 6: Combination Therapy with BTG945 and Other Anti-CancerTherapies for Platinum Sensitive Stage III and IV Platinum-SensitiveRecurrence Cancers

Consideration may be given to bevacizumab either alone or withcarboplatin/gemcitabine but the use of this agent is stillcontroversial. Platinum-sensitive recurrence: If recurrence occurs >6 mofrom initial or subsequent complete clinical response toplatinum-containing chemotherapy, the patient should be treated with 12mg/m² BTG945 administered IV in saline for injection on day 1 and day 15of a 28 day cycle over 1 hour up to a maximum of 6 cycles together withone of the IV platinum-containing combination regimens below.

Example 6.1 Bevacizumab 15 mg/kg IV (initially over 90 min, then over 60min, and finally over 30 min for subsequent infusions); every 21 d untildisease progression, irrespective of prior platinum response

Example 6.2 Gemcitabine 1000 mg/m² IV over 30 min on days 1 and 8 pluscarboplatin AUC 4 IV push on day 1; every 21 d for 6-10 cycles plusbevacizurnab 15 mg/kg IV on day 1 prior to gemcitabine and carboplatinand continued until progression of disease or unacceptable toxicity

Example 6.3 Bevacizumab 10 mg/kg IV every 14 d in combination with oneof the following IV chemotherapy regimens: paclitaxel, pegylatedliposomal doxorubicin, or topotecan (topotecan is given weekly)

Example 6.4 Bevacizumab 15 mg/kg IV every 21 d in combination withtopotecan (every 21 d)

Example 6.5 Bevacizumab 15 mg/kg IV (initially over 90 min, then over 60min, and finally over 30 min for subsequent infusions); every 21 d untilprogression

Example 6.6 Bevacizumab 10 mg/kg IV on days 1 and 15 plus topotecan 4mg/m 2 IV on days 1, 8, and 15, q 28 days

Example 7: Combination Therapy with BTG945 and Platinum-Sensitive orResistant or Refractory BRCA-Mutated Stage III and IV Platinum-SensitiveRecurrence Cancers

For patients diagnosed as BRCA-mutated (as detected by an FDA-approvedtest, BRACAnalysis CDx™) in patients who have been treated with three ormore prior lines of chemotherapy: 12 mg/m² BTG945 administered IV insaline for injection on day 1 and day 15 of a 28 day cycle over 1 hourup to a maximum of 6 cycles whilst Olaparib 400 mg is administered POBID continuously

In the European Union, olaparib 400 mg PO BID is approved as monotherapyfor the maintenance treatment of adult patients with platinum-sensitive,relapsed, BRCA-mutated (germline and/or somatic) high-grade serousepithelial, fallopian tube, or primary peritoneal cancer who are showingresponse (complete or partial) to platinum-based chemotherapy.

1-100. (canceled)
 101. A method of treating cancer in a patient in needthereof comprising administering to the patient a compound of formula I

or a pharmaceutically acceptable salt or ester thereof, wherein: thecancer has the characteristic of being a type prone to being or becomingrefractory or resistant to platinum drug based therapy, the compound orpharmaceutically acceptable salt or ester thereof is administered to thepatient at a dose of from 6 mg/m² to 14 mg/m² of compound orpharmaceutically acceptable salt or ester thereof per patient bodysurface area per administration, and each of the administrations is in a28-day cycle at 14-day intervals.
 102. The method according to claim101, wherein the administration is in a first dose on day 1 of the28-day cycle and a second dose on day 15 of the 28-day cycle.
 103. Themethod according to claim 101, further comprising administering atherapeutically effective amount of one or more further anticanceragents.
 104. The method according to claim 102, further comprisingadministering a therapeutically effective amount of one or more furtheranticancer agents.
 105. The method according to claim 101, furthercomprising administering a PARP inhibitor to the patient.
 106. Themethod according to claim 101, wherein the PARP inhibitor is chosen fromolaparib, rucaparib, and niraparib.
 107. The method according to claim102, further comprising administering a PARP inhibitor to the patient.108. The method according to claim 102, wherein the PARP inhibitor ischosen from olaparib, rucaparib, and niraparib.
 109. The methodaccording to claim 101, wherein the cancer is chosen from cancersexpressing α-folate receptors (FR-α).
 110. The method according to claim101, wherein the cancer is ovarian cancer.
 111. The method according toclaim 101, wherein the cancer is epithelial ovarian cancer, fallopiantube cancer, or peritoneal cancer.
 112. The method according to claim101, wherein the cancer is serous ovarian cancer.
 113. The methodaccording to claim 101, wherein the cancer is High-Grade Serous OvarianCancer (HGSOC).
 114. The method according to claim 101, wherein the doseis administered intraperitoneally (IP) or intravenously (IV).
 115. Themethod according to claim 101, wherein the administration is an infusionof from 11.5 mg/m² to 12.5 mg/m² per administration.
 116. The methodaccording to claim 101, wherein the administration is an infusion ofabout 12 mg/m² per administration.
 117. The method according to claim101, wherein the treatment is with a cumulative maximum of 150 mg/m² ofcompound or pharmaceutically acceptable salt or ester thereof perpatient body surface area over the course of all the administrations.118. The method according to claim 101, wherein the compound is thetrisodium salt of formula II:


119. The method according to claim 118, further comprising administeringa PARP inhibitor to the patient.
 120. The method according to claim 119,wherein the PARP inhibitor is chosen from olaparib, rucaparib, andniraparib.
 121. The method according to claim 119, wherein the trisodiumsalt of formula II and the PARP inhibitor are administered to thepatient separately.
 122. The method according to claim 120, wherein thetrisodium salt of formula II and the PARP inhibitor chosen fromolaparib, rucaparib, and niraparib are administered to the patientseparately.
 123. The method according to claim 118, wherein thetreatment is with a cumulative maximum of 150 mg/m² of compound orpharmaceutically acceptable salt or ester thereof per patient bodysurface area over the course of all the administrations.